Here they have lots of information booklets on the area but the key booklet to get is this one.
It lists all the events that are taking place in Terreros during July & August. If we look at the page for today, there is a dancing exhibition on the Paseo Marítimo at 22.00 (yes, a lot takes place late at night because of the heat during the day), there's Yoga at 18.00 in the Cultural Centre and children's basketball in the court on the Paseo.
There's a few concerts up at the Castle during the summer, including one this Sunday and this Saturday there is the Romería Virgen del Carmen, who is the patron saint of fishermen (romería = picnic & procession) starting at 21.00.
Last year during August there was also a large notice board on the Paseo listing all the events for the month - and there was a lot to do.
Keep an eye open for noticed by the Supermarkets and in the bars as these will give you additional information on events that are taking place.
And enjoy summer in Terreros.